Expanded metal structures are known in which a metal sheet or foil is slit or perforated to leave at each of its sides a solid band or strip, and these sides are then stretched to expand the slit or perforated portion. Usually, the solid side bands are rolled to increase their length. These solid bands are thus of the same length as the surface length of the expanded portion of the slit or perforated structure. There results a structure expanded in certain regions and solid in other regions. Such stretching of the sides decreases their thickness so the sides are thinner than the expanded material regions.
Such structures have, in certain applications, for example, in the manufacture of fluid or liquid filters, the disadvantage of requiring exterior dimensions which are relatively large for a given expanded metal suface area, and thus the area of filtering, because of the stretching or rolling of the side bands.
In addition, manufacture is relatively complex, because two unwinding operations are required and the second operation requires rolling the lateral bands to expand the perforated regions of material.